1. Field of the Invention
The present invention relates to an information processing apparatus and method, and a program therefor. In particular, the present invention relates to an information processing apparatus and method, and a program therefor which enable moving out and moving back of a part of a content with greatly simplified processing.
2. Description of the Related Art
In recent years, contents such as video, audio, and the like are widely used, and use of recording/reproduction apparatuses capable of recording and reproducing these contents as digital data is also spreading. For example, use of recording apparatuses capable of storing broadcast contents as digital data in a digital versatile disc (DVD) or a hard disc drive (HDD) is rapidly spreading. In addition, digital terrestrial broadcasting has recently been started after digital broadcasting that employs a broadcasting satellite. In such digital broadcasting, high definition television (HDV) video, which has a higher resolution than video that is broadcast in traditional broadcasting, is broadcast, and development of a recording apparatus that is capable of recording such a broadcast content on an optical disk or the like while maintaining picture quality thereof is advancing.
The term “content” refers to a variety of matters created by human creative activities. Examples of the contents include films, music, dramas, literature, photographs, comics, animation, computer games, other types of written, graphic, color-based, audio, motion-based, and video matters, a combination of the above, and a program for providing information related to the above via a computer. Note that, in the present specification, so-called content data, i.e., matters created by the human creative activities and converted by a device into a processible form, such as an electrical signal, or fixed on memory, for example, is also referred to as a content.
As described above, at present, it is easy to store high-quality contents in portable storage media. Accordingly, importance of protection of copyright of the contents is increasing. As a method for protecting copyright of video contents, a method of adding copy control information (CCI), which represents whether or not copying of a video content is possible, to the video content is normally employed at present. For example, use of the copy control information enables the video content to enter a Copy Free state, in which copying is not restricted, a Copy Once state, in which copying is permitted only once, a Copy Never state, in which copying is prohibited, or the like. In the current digital broadcasting mentioned above, copy control information representing “Copy Once” is added to all contents, and the recording apparatus normally causes such a content to enter the Copy Never state before recording the content on a storage medium.
A video content recorded on the storage medium after being caused to enter the Copy Never state is permitted to be copied to another storage medium on the condition that data of the video content be deleted from the storage medium. This operation of copying the data to the other storage medium while deleting the original data is called “Move”. Thus, in the case where a video content has been received by the recording apparatus via digital broadcasting or the like and recorded on an HDD within the recording apparatus, for example, if a user desires to keep the video content for a long period of time, the user is able to move the video content to a removable medium such as a DVD. Thus, user convenience is improved while preventing unlawful production of copies in large quantities.
In general, the content to be moved is encrypted in a source from a moving source. Thereafter, the content encrypted (hereinafter referred to as the encrypted content) is copied to a moving destination together with information (hereinafter referred to as identification information) for identifying the encrypted content, e.g., information composed of key information for decrypting the encrypted content, a protected content ID, and the like.
Further, the encrypted content copied to the moving destination can be copied back to the moving source on the condition that the content be deleted from the moving destination. That is, a first moving, from the moving source to the moving destination, and a subsequent second moving, from the moving destination to the moving source, are possible. Hereinafter, the first moving and the second moving will be referred to as moving out and moving back, respectively.
As known apparatuses enabling moving out and moving back, apparatuses disclosed in Japanese Patent Laid-open No. 2006-4543 (US 2005-0281540 A1)(referred to as Patent Document 1 hereinafter) and Japanese Patent Laid-open No. 2006-107165 (referred to as Patent Document 2 hereinafter) can be cited, for example.
Known apparatuses, such as those disclosed in Patent Document 1 and Patent Document 2, have a problem in that in the case where an object to be moved is not the entire content but a part of the content, time-consuming processing may be required for both moving out and moving back.
This problem will now be described below with reference to FIGS. 1 to 3.
Referring to FIG. 1, it is assumed that, in a known moving source device 1, an encrypted content 11, which is a candidate for an object to be moved, and identification information 12 including key information A and a protected content ID are held in a single file.
In this case, although not shown, in the case where the object to be moved is the entire encrypted content 11, the moving source device 1 copies the encrypted content 11 as it is and the identification information 12 to a moving destination device 2-A or 2-B, and deletes the encrypted content 11 (i.e., the original data) and so on within itself, thereby completing moving out.
In contrast, in the case where the object to be moved is a part of the encrypted content 11 (hereinafter referred to as an encrypted part), specifically, in the case where, as illustrated in FIG. 2, an object to be moved to the moving destination device 2-A is an encrypted part 11-1 and an object to be moved to the moving destination device 2-B is an encrypted part 11-2, for example, moving out necessitates the following time-consuming series of processes.
That is, since direct extraction of the encrypted parts 11-1 and 11-2 from the encrypted content 11 is difficult, the moving source device 1 decrypts the entire encrypted content 11 using the key information A. As a result, the encrypted content 11 is converted back to a non-encrypted content.
The moving source device 1 extracts a non-encrypted part corresponding to the encrypted part 11-1 from the non-encrypted content, and re-encrypts the extracted non-encrypted part to generate an encrypted content 21-1. Thus, the new encrypted content 21-1 corresponding to the encrypted part 11-1 is generated. At the time of this re-encryption, an encryption key different from an encryption key used for the encrypted content 11 is used. Accordingly, the moving source device 1 generates key information B necessary for decrypting the encrypted content 21-1, i.e., key information B different from the key information A, and also generates a protected content ID for the encrypted content 21-1, thereby generating identification information 22 containing them. Thus, the new identification information 22 different from the identification information 12 is generated for the new encrypted content 21-1.
Then, the moving source device 1 copies the encrypted content 21-1 and the identification information 22 to the moving destination device 2-A.
Similarly, the moving source device 1 extracts a non-encrypted part corresponding to the encrypted part 11-2 from the non-encrypted content, and re-encrypts the extracted non-encrypted part to generate an encrypted content 21-2. Thus, the new encrypted content 21-2 corresponding to the encrypted part 11-2 is generated. At the time of this re-encryption, an encryption key different from the encryption keys used for the encrypted content 11 and the encrypted content 21-1 is used. Accordingly, the moving source device 1 generates key information C necessary for decrypting the encrypted content 21-2, i.e., key information C different from the key information A or B, and also generates a protected content ID for the encrypted content 21-2, thereby generating identification information 23 containing them. Thus, the new identification information 23 different from the identification information 12 or 22 is generated for the new encrypted content 21-2.
Then, the moving source device 1 copies the encrypted content 21-2 and the identification information 23 to the moving destination device 2-B.
As described above, in order to copy the encrypted part 11-1 (actually, the encrypted content 21-1) and the encrypted part 11-2 (actually, the encrypted content 21-2) to the moving destination device 2-A and the moving destination device 2-B, respectively, the time-consuming series of processes, i.e., the decryption of the encrypted content 11, the re-encryption for generating the new encrypted contents 21-1 and 21-2, and generation of the new identification information 22 and 23, may be required.
In addition, in order to complete the moving out, deletion of the original data in the moving source device 1, i.e., deletion of the encrypted parts 11-1 and 11-2, may be required. This deletion necessitates the following time-consuming processes. That is, the moving source device 1 deletes the new encrypted contents 21-1 and 21-2. In addition, the moving source device 1 re-encrypts a non-encrypted part that is not the object of moving among the non-encrypted content using the encryption key corresponding to the key information A to generate an encrypted part 11-3, and holds the generated encrypted part 11-3 in the original file so as to be associated with the identification information 12. As a result of the above series of processes, a process equivalent to the deletion of the encrypted parts 11-1 and 11-2 is completed.
The moving out of the encrypted part 11-1 to the moving destination device 2-A and the moving out of the encrypted part 11-2 to the moving destination device 2-B are completed after the above time-consuming series of processes are performed.
As illustrated in FIG. 3, when moving back of the encrypted content 21-1 from the moving destination device 2-A to the moving source device 1 has been performed, the encrypted content 21-1 is held, in the moving source device 1, in a file different from the file of the original encrypted content 11, i.e., the file in which the encrypted part 11-3 is stored at the time of the moving back. Similarly, when moving back of the encrypted content 21-2 from the moving destination device 2-B to the moving source device 1 has been performed, the encrypted content 21-2 is held, in the moving source device 1, in a file different from the file of the original encrypted content 11, i.e., the file in which the encrypted part 11-3 is stored at the time of the moving back.
However, completion of the moving back from the moving destination devices 2-A and 2-B to the moving source device 1 means that a state as illustrated in FIG. 1 is achieved again; that is, reconstruction of the encrypted content 11 and storage thereof in the original file is necessary.
The reconstruction of the encrypted content 11 necessitates the following time-consuming processes.
That is, the moving source device 1 decrypts the encrypted part 11-3 using the key information A. The moving source device 1 also decrypts the encrypted content 21-1 corresponding to the encrypted part 11-1 using the key information B. The moving source device 1 also decrypts the encrypted content 21-2 corresponding to the encrypted part 11-2 using the key information C.
Next, the moving source device 1 combines the three non-encrypted parts obtained by the above three decryption processes to generate a non-encrypted content.
Next, the moving source device 1 re-encrypts the generated non-encrypted content using the encryption key corresponding to the key information A to reconstruct the encrypted content 11.
Then, the moving source device 1 holds the reconstructed encrypted content 11 in the original file so as to be associated with the identification information 12.
After the above time-consuming series of processes are performed, the state illustrated in FIG. 1 is achieved again, and the moving back from the moving destination devices 2-A and 2-B to the moving source device 1 is completed.